1. Field of the Invention
The present invention relates to surfactant systems and their incorporation into cleaning compositions useful in household detergents and other related uses. More particularly, the invention relates to the enhancement of soil release compositions that not only clean fabrics and articles of clothing but prevent the re-deposition of soils and stains thereon.
2. Background Discussion
Soil release agents are key ingredients in cleaning compositions, i.e., textiles, laundry and hard surfaces such as carpet-cleaning and textile treating.
These soil release agents are commonly applied to the fabric during the manufacture of clothing or textile fiber. The primary purpose of the soil release agents is to make it easier to clean the textile fibers by home cleaning methods using conventional household machines or cleaners.
For example, in most laundering processes such as conventional home washing machines or hand washing with detergent bars, it is usually very difficult to remove soil and/or oily stains from textile material. Moreover, even assuming that the undesirable materials are removed from the textile and/or a fairly clean textile material is being washed, oftentimes soil remaining in the wash water is redeposited onto the textile material prior to the end of the wash cycle. Hence, when the textile material is removed from the washing machine and subsequently dried, it has not been properly cleaned. Thus, textile materials after use rarely assume a truly clean appearance, but instead tend to gray and/or yellow due to the soil and/or oily materials being deposited or redeposited and remaining thereon.
Also, synthetic fibers and fabrics having synthetic fibers incorporated therein or those made entirely of synthetic fibers are hydrophobic and oleophilic. Therefore, the oleophilic characteristics of the fiber permit oil and grease to be readily embedded in the fiber, and the hydrophobic properties of the fiber prevent water from entering the fiber to remove the contaminants and dirt therefrom.
One solution to the soil removal and soil redeposition problem is to deposit a finish onto the fiber to impart a hydrophilic character to the fiber. Attempts have been made to reduce the oleophilic characteristics of these synthetic fibers by coating the fibers with a coating that is oleophobic, i.e., one that will hinder the attachment of soil and oil materials to the fibers. Many polymer systems have been proposed which are capable of forming a film around the textile fibers, particularly acid emulsion polymers prepared from organic acids having reactive points of unsaturation. These treating polymers are known as soil-release agents.
Typical soil release agents that have been developed for synthetic fibers and fabrics are the copolymers of ethylene glycol and terephthalic acid for the treatment of Dacron, Fortrel, Kodel and Blue C Polyester, trademarks of various synthetic fibers and fabrics.
Among the leading soil release agents developed for laundering purposes are the polyesters exemplified in U.S. Pat. No. 5,134,223 to Langer, et al.; U.S. Pat. No. 4,999,128 to Sonnenstein; U.S. Pat. Nos. 4,937,277; 4,804,483 and 4,873,003 to O'Lenick, et al.; U.S. Pat. No. 4,861,502 to Caswell; U.S. Pat. No. 4,861,512 to Gosselink; U.S. Pat. No. 4,787,989 to Fanelli, et al.; U.S. Pat. 3,962,152, 3,416,952, and 4,132,680 to Nicol; U.S. Pat. Nos. 4,201,824, and 4,349,688 to Sandler and U.S. Pat. No. 4,116,885 to Derstadt, et al. Generally these agents are polyester polymers containing terephthalate and/or urethane groups to improve water compatibility.
The term "soil-release" in accordance with the present invention refers to the ability of the fabric to be washed or otherwise treated to remove soil and/or oily materials that have come into contact with the fabric. The present invention does not wholly prevent the attachment of soils or oily materials to the fabric, but hinders such attachment and improves the cleanability of the fabric.
Concentrated solutions of soil-release polymers have been padded onto fabrics by textile manufacturers to impart a permanent soil-release finish to the fabric. As the amount of soil-release polymer on the fabric is increased, the ability of the fabric to release soil is increased. However, fabrics with this permanent soil-release finish possess many disadvantages. As the amount of soil-release polymer on the fabric is increased, the fabric has a tendency to become stiff and lose the desirable feel of the fabric. Thus, the upper limit on the amount of soil-release polymer to be used is determined by economics and the resulting adverse effect it has on the fabric. Fabrics with a heavy application of soil-release polymer do not have the same desirable appearance and feel as the same fabrics without the soil-release coating. Thus, practically speaking, there is a set concentration range of the soil-release agent that can be applied that is also dictated by commercial requirements.
Some soil-release polymers are effective fabric treating agents even at very low levels on the fabric at which the appearance and feel of the fabric are not adversely affected. Thus, this property offers an ideal method of treating a synthetic fiber-containing fabric which would be to reapply a very small amount of soil-release polymer to the fabric each time the fabric is washed.
Moreover, the soil release agent is preferably reapplied when the fabric is washed because the original soil release agent, applied to the fabric during manufacture, washes out after repeated washing by the consumer.
The problem is to get the soil release agent in the detergent solution to adequately deposit and remain on the clothing being washed. A number of theories have been proposed to explain the difficulties encountered when one tries to enhance this soil release agent deposition during the wash process. One theory suggests that the surfactants in the detergent may complex with or adsorb onto the soil release agent, thus inhibiting its deposition onto the fabric. Another theory has proposed that the main cleaning surfactants in the detergent compositions compete with the soil release agents for sites on the fabric. This competition prevents the soil release agents from getting to the fabric.
Anionic surfactants such as alkylbenzenesulfonates, alkylether sulfates, etc., are the major active cleaning agents in most laundry detergent systems. They are known to have antagonistic effects on the polymer deposition and interfere with the soil release polymer's properties. These antagonistic effects are further exacerbated because anionic surfactants are generally used at high concentrations for general soil and stain removal performance in most commercial detergent compositions.
U.S. Pat. No. 5,565,145 to Watson, et al. discloses detergent compositions comprising cleaning and soil dispersing agents that consist of ethoxylated/propoxylated polyalkyleneamine polymers. The detergents are allegedly useful in the cleaning of fabrics and hard surface areas.
U.S. Pat. No. 5,332,528 to Pan, et al. discloses detergent compositions containing one or more anionic primary surfactants and a soil release composition consisting of a soil release agent and an anionic surfactant interactive nonionic hydrophile and/or an anionic surfactant interactive hydrophobic moiety or both, together with a soil release agent enhancer consisting of a polyhydroxy fatty acid amide.
Prior to the present invention, the synergistic benefits of mixtures of certain classes of surfactants and soil release agents were limited to combinations of SRPS and polyhydroxy fatty acid amides. It would be a major achievement to provide other detergent additives that would enhance the deposition of soil release agents onto the textile material being washed by the consumer and thus provide long lasting soil release properties for the life of the material.
The present invention relates to compositions and methods of use of certain specific surfactants that are able to dramatically lower the critical micelle concentration (cmc) of anionic laundry deterrent and other cleaning systems which thereby allows for the better deposition of polymeric soil release agents onto the fabrics being washed. More particularly, the present invention relates to compositions and methods of use of low concentrations of amphoteric and long chain nonionic alkoxylate surfactants to enhance the deposition of polymeric soil release agents in the presence of typical detergent ingredients, especially highly anionic surfactant systems.
A further object of the present invention is to provide detergent compositions with enhanced soil release properties. More specifically, an object of the present invention is to provide textile detergent compositions comprising a soil release agent and at least one surfactant that dramatically lowers the critical micelle concentration (cmc) of the system. Another object of the present invention is to provide detergency and soil release benefits in compositions which also act as fabric softeners. These and other objects will become apparent from the description of the invention in the present specification.